Trying to find what change caused pdf document to spill to 2nd page

I have 2 pdf documents that are almost identical but one spills over to a 2nd page and I cannot see why. I have compared the 2 using adobe comparison and that hasn't answered by questions and if anoything it created new ones, e.g.

1. It says Graphic Element Attributes Changed but it doesn't say what attributes have changed. This is in reference to a horizontal line going across the document. It looks to me that the line is bold/fatter in the 2nd version but I don't know what formatting caused it. Or maybe the line is in a different font ?

2. I see a piece of text where in one version end of line is "...double digits" and the other is "...double digits and", so the word "and" is on the same line in the 2nd version but in the 1st one spills over to the next line and I cannot see why. Adobe does not repoort it as a difference.

3. There are many instances of what looks to me like no change reported as change, e.g. in one version we have "20.3x" and the same is in the 2nd version but it is reported as DELETED and then as INSERTED.

4. There seems to be a font change and I have no idea how that could occur but one of the differences is from DejaVuSans to DejaVuSans-Bold (possibly related to the line in point 1). How could this occur if the software used to generate both docs is (supposedly) the same although on different servers. Could the fonts be defined differently?

Font "DejaVuSans" changed to "DejaVuSans-Bold".

Font-size "3.98824" changed to "0".

Font-color changed.

[ how can font size be changed to '0'?]

The bottom line is I don't know how to find the cause of spilling to page 2. My hunch is that it is something to do with the font and it being bold just pushed something over the limit. However, my other idea is that perhaps the 2 docs differ in page definition: one could be slightly bigger?

One thing that I would like to try out and don't know how is "make the documents the same step by step". So when the Adobe Compare tools says that something is different, eliminate the changes one by one and the 2 docs are the same.

Can anyone offer any suggestions? Thank you.